Extended-spectrum beta-lactamases in Klebsiella spp and Escherichia coli obtained in a Brazilian teaching hospital: detection, prevalence and molecular typing

Abstract

His study was performed to compare the methods of detection and to estimate the prevalence of extendedspectrum β-lactamases (ESBL) among Klebsiella spp and E. coli in a university hospital in southern Brazil. We also used a molecular typing method to evaluate the genetic correlation between isolates of ESBL K. pneumoniae. Production of ESBL was investigated in 95 clinical isolates of Klebsiella spp and Escherichia coli from Hospital de Clínicas de Porto Alegre, using Kirby-Bauer zone diameter (KB), double-disk diffusion (DD), breakpoint for ceftazidime (MIC CAZ), increased zone diameter with clavulanate (CAZ/CAC) and ratio of ceftazidime MIC/ceftazidime-clavulanate MIC (MIC CAZ/CAC). Molecular typing was performed by DNA macrorestriction analysis followed by pulsed-field gel electrophoresis. The KB method displayed the highest rates of ESBL (up to 70% of Klebsiella and 59% of E. coli), contrasting with all the other methods (p < 0.05). The confirmatory methods (DD, MIC CAZ, CAZ/CAC and MIC CAZ/CAC) showed a range of ESBL production from 8 to 13% for E. coli and from 33 to 40% for Klebsiella species. Therefore, the KB method was useful only as a screening method as it provided several false positive results. Molecular typing of 17 ESBL K. pneumoniae indicated that the isolates had no clonal relation. We found a good correlation among the confirmatory methods for ESBL detection although the methods which evaluate inhibition of the β-lactamase by clavulanate appeared to be more specific. The high prevalence of ESBL Klebsiella in our hospital is probably due to individual selection of resistant strains rather than the transmission of a common strain.

Nosocomial infection and characterization of extended-spectrum β-lactamases-producing Enterobacteriaceae in Northeast Brazil

“…Similar results have been reported in members of the family Enterobacteriaceae 7,13,18,19 and in a multicenter study investigating bacterial resistance in Brazilian hospitals 6 . In contrast, E. coli was found to be the most prevalent ESBL-producing microorganism in Saudi Arabia 1 , France 16 and Italy 15 .…”

“…A study conducted in Spain detected ESBLproducing strains in 90% of hospitals participating in a surveillance program. These findings demonstrate that the prevalence of ESBL-producing strains varies from country to country 2,7,8 . Because of the increasing incidence of ESBL-producing Gramnegative bacteria and the lack of standardized phenotypic methods for the detection of ESBLs in a larger range of microorganisms, this study aimed to characterize ESBL-producing Enterobacteriaceae isolated at hospitals in northeast Brazil, focusing on the evaluation of their antimicrobial susceptibility profile.…”

Enterobactérias produtoras de ESBL em Passo Fundo, estado do Rio Grande do Sul, Brasil

“…Os principais gêneros produtores de ESBLs, dentre as enterobactérias, são Escherichia coli, Klebsiella pneumoniae, Proteus sp, Providencia sp e Enterobacter sp 2 . Enterobactérias produtoras de ESBLs estão amplamente disseminadas, já tendo sido reportadas na França, Estados Unidos, Reino Unido, Grécia, Holanda, Hungria, Portugal, Bolívia, Peru, Brasil, entre outros [9][10][11][12][13] .…”

Métodos de triagem e de confirmação para detecção de BLEAs (beta lactamases de espectro ampliados) em isolados de Klebsiella pneumoniae

“…However, Freitas et al (2003) suggest that the KB method was useful only as a screening since it provided several false positive results. In this study, results obtained in KBD were better indicators of ESBL production than the breakpoints in automated system of microdilution method.…”